Israeli billionaire Dan Gertler sold one of his Congo-based oil companies to the country’s government last year for $150 million.
Roughly 300 times the amount paid for the oil rights.
The deal has been criticized by transparency campaigners.
Gertler has close links to the Kinshasa government, but denied any wrongdoing regarding the sale of Nessergy Ltd, which paid a $500,000 for its block in 2006.
The block lies near neighbor Angola’s most productive oilfields. When it was acquired by Nessergy, the block was located in an area at the heart of a maritime border dispute between Kinshasa and Luanda.
According to the contract for the April 2013 transaction seen by Reuters, Sonangol financed the deal, paying Gertler’s Fleurette Group $150 million for the rights to the block.
Congo will repay Sonangol out of future oil revenue.
Gertler has been paid the fee but cannot access the money until a deal between the national oil companies of Congo and Angola is finalized.
A Fleurette representative said no major drilling had taken place in the Nessergy block due to disputes over development rights.